COMPARATIVE PATHOLOGY CORE ABSTRACT In vivo model organisms operate in a systems biology framework integrating all levels of biological organization - biomolecule, pathway, cell, organ, organism and inform us of potential adverse human health outcomes. For this reason, animal models remain the gold standard for studying the effects of environmental toxicants on development, cancer, reproduction, organ toxicity, neurological and endocrine systems - understanding these adverse effects requires pathologic evaluation of the affected cells and organs. The mission of the Center for Human Health and the Environment (CHHE) Comparative Pathology Core (CPC) is to provide pathology expertise to CHHE members to assess the effects of environmental factors in diverse animal models. CPC pathologists and a network of pathologists with specialized organ system expertise will provide advanced pathology evaluation for CHHE member projects and maximize pathologists collaborations with CHHE members leading to joint-authored grant submissions and publications in environmental health science (EHS). To further enhance CHHE member capabilities, the CPC will work closely with the Systems Technologies Core utilizing laser-capture micro- dissection to isolate specific cellular subpopulations from lesional tissues of animal models for advanced biomolecule assessments - proteomics, genomics and metabolomics. The CPC is located at an internationally recognized College of Veterinary Medicine and will be a gateway for CHHE members to access Companion Animal Diseased Tissue Archives, The Center for Comparative Medicine and Translational Research, and a large companion animal hospital population to develop innovative companion animal models of human environmental health diseases to compliment traditional models and to speed translation of EHS research to solve human disease. CPC training in pathology techniques and tissue assessment methods will expand EHS animal model research capability of the CHHE.